The Pliocene (5,3-1,8 MY)

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1 The Pliocene (5,3-1,8 MY) - transition towards the Ice Age - Jarðsaga 2 Ólafur Ingólfsson Háskóla Íslands

2 Definition of the Pliocene Pliocene (very recent), was defined from marine sediments in Italy which contain essentially modern fossil fauna

3 In Pliocene, continental configuration becomes modern

4 Pliocene tectonics A very important tectonic event was when S America reapproached North America for the first time since the Cretaceous period, almost 100 million years earlier. The Panamanian Isthmus emerged due to tectonics and fluctuating sea levels.

5 Pliocene Ocean Currents Warm shallow ocean currents weaved between the Pliocene continents. Cooler shallow currents were restricted to the N Atlantic, and the Antarctic. Deeper, cooler currents flowed from the Antarctic into the Atlantic.

6 Pliocene SST Differences from modern values values for two selected months in C.

7 Pliocene and modern vegetation global albedo distribution

8 Pliocene vegetation The climate cooled and dried as the World moved from the Miocene into the Pliocene. The climate became sharply seasonal, similar to the modern day. However, more dramatic changes were afoot...

The peat accumulated in a beaver pond surrounded by boreal larch forest near regional tree line in coastal hills close to the Arctic

9 Still warm at high latitudes in early Pliocene A peat deposit on Ellesmere Island, Nunavut, Canada, allows a unique glimpse of the Early Pliocene terrestrial biota north of the Arctic Circle. The peat accumulated in a beaver pond surrounded by boreal larch forest near regional tree line in coastal hills close to the Arctic Ocean. The ecological affinities of the plant and beetle remains contained in the peat indicate that winter temperatures on Ellesmere Island were nearly 15 C higher and summer temperatures 10 C higher than they are today.

10 Pliocene life in the Oceans ThePlioceneOceansweremoderninthatallmajorgroups of marine mammals, fish, invertebrates, plankton and corals were in place, and even on the species level, 50-90% of presently living marine species were already there.

11 Miocene-Pliocene development of whales TheMiocene-Pliocenewarm seas teemed with life. The whales evolved and most present groups were already in place in Pliocene. Below: Porpoise ( höfrungar ) evolution.

12 Pliocene marine top predators Toothed whales and seals, together with sharks, have remained top predators in the Oceans since Miocene times.

Megalodon and the Great White Carcharocles megalodon was

modern great white shark Carcharodon carcharias.

m; at least three times the size of the great white.

13 Megalodon and the Great White Carcharocles megalodon was a giant shark similar to, but much larger than, the modern great white shark Carcharodon carcharias. The maximum size reached by Megalodon was probably m; at least three times the size of the great white. Megalodon became extinct at the end of the Pliocene, about 1,6 MY ago...

14 The Great Barrier Reef - a bridge back in time - The Great Barrier Reef partly steems back to the Miocene, 25 MY ago. Its relatively stable environments have been the breeding grounds through time for thousands of species of animals and plants... Stretching > 2000 km and covering >25,000 km 2 the Great Barrier Reef is the world s largest coral reef and probably the richest. More than 1500 species of fish, 4000 species of molluscs, 400 species of sponge and 300 species of hard corals live here.

15 South America: Bird continent... S America has more species than any other continental region, and over a third of all the world's species. This bird fauna, as well as being extremely rich, is highly distinctive, with 22 endemic families. Evidence from DNA sequences makes it almost certain that a very large part of the S American bird fauna is authochthonous - that is, it originated and diversified in place.

16 More on bird evolution... By late Tertiary, the avifauna was basically modern, with many presently living species present. The spread of grasslands favoured birds in open habitats, especially the song-birds (söngfuglar, spörfuglar)

Great diversity of song-birds Songbirds have developed rich and complex

They sing to court and they sing to fight, conserving their energy for

Songbirds, as their name implies, sing complex and elegant melodies.

Instead of fighting, an energy-intensive action, they sing to defend

17 Great diversity of song-birds Songbirds have developed rich and complex songs for mating and territorial displays. They sing to court and they sing to fight, conserving their energy for important tasks like eating and mating. Songbirds, as their name implies, sing complex and elegant melodies. All birds sing songs, but songbirds REALLY sing. Instead of fighting, an energy-intensive action, they sing to defend territories, attract the opposite sex and to sound alarms. Birds, like humans, have distinct accents developed from where they grew up. Singing is learned from tutor.

Pliocene Australia Australia was close to its present global position. The continental plate carrying Australia had collided with the South East Asian plate.

18 Pliocene Australia Australia was close to its present global position. The continental plate carrying Australia had collided with the South East Asian plate. Australia's climate was warm and wet but soon began to dry again. Australia's forests were dominated by gum and wattle trees ( gúmmí- og tágafléttutré ). A dazzling mixture of wildflowers blossomed in the open spaces.

Pliocene animals of Australia Agile Wallaby (Macropus agilis) is the most common kangaroo of

19 Pliocene animals of Australia Agile Wallaby (Macropus agilis) is the most common kangaroo of tropical Australia. The Saltwater Crocodile is the world's largest living reptile. 9 m long and weighs >900 kg! The extinct Bluff Downs Python is the largest snake ever to have lived - 10 m long with a 0.3 m girth. Many animals such as Agile Wallabies and Saltwater Crocodiles made their appearance for the first time. Most of the older marsupials animals also remained. In some animal groups, giant species evolved for example, the largest snake that ever lived, a 10 m long python.

A Pliocene-Pleistocene giant lizzard The name Megalania prisca means

the largest of which today is the Komodo Dragon found in Indonesia.

20 A Pliocene-Pleistocene giant lizzard The name Megalania prisca means the ancient giant butcher, and this may certainly have been a fitting description for this large meat eater. Megalania belonged to the family that includes the monitor lizards, the largest of which today is the Komodo Dragon found in Indonesia. It was 4-5 m long, scavanger and killer. Rumour has it that it still exists in remote areas in Indonesia...

Island-hopping causes new immigrant species The Australian Water Rat or Beaver Rat is aquatic and occurs wherever suitable habitat is provided by rivers, swamps, marshes, backwaters,

21 Island-hopping causes new immigrant species The Australian Water Rat or Beaver Rat is aquatic and occurs wherever suitable habitat is provided by rivers, swamps, marshes, backwaters, or estuaries New groups of animals were arriving from South East Asia via island chains. Among these were Australia's first rats and mice. These did not threaten the ruling marsupials.

The rodents were as successful as ever, and in Asia, elephants and stegodonts were successful.

22 Pliocene Eurasia 1 Rock Hyrax an elephant rodent The mixture of animals we know today in Eurasia took shape in the Pliocene. The rodents were as successful as ever, and in Asia, elephants and stegodonts were successful. Hyraxes ( hnubbar ) also moved across from Africa. Horses suffered a slight decline in diversity, but tapirs and rhinos, continued to survive throughout Eurasia.

23 Elephant evolution The family Elephantidae is the root from which the mammoth, Asian elephant, and African elephant came from. Interestingly, the Asian elephant is more closely related to the extinct mammoth than to the African elephant.

24 Deinotherium, only distantly related to elephants proper, these animals are distinguished by its downturned tusks. Appearing during the Miocene, they grew progressively larger, and grew as big as the biggest elephant. They flourished in Africa, Europe, and parts of Asia, but became extinct in early Pleistocene.

The South America species, Smilodon populator, was even larger. Cows and antelopes were successful throughout Eurasia.

25 Pliocene Eurasia 2 Smilodon, the famous sabre-toothed cat, is well known because of the enormous numbers of skeletons of the North America species Smilodon fatalis, beautifully preserved in the tar pits of La Brea in California. The South America species, Smilodon populator, was even larger. Cows and antelopes were successful throughout Eurasia. The camels, which developed in N America, crossed into Asia. Hyaenas and the first sabre-toothed cats developed in Eurasia.

retreated, whereas N Africa was still largely warm and

26 Pliocene drying-out of the Mediterranean area During Pliocene, the Mediterranean area dried out and the forests retreated, whereas N Africa was still largely warm and humid, with extensive forests bordering the East African savannas.

ago the seafloor consisted of several basins of variable size and topography, with depths

27 The Mediterranean Sea dries out! The Mediterranean Sea (2,510,000 km 2 ) became isolated during the Miocene, and about 6-5 MY ago the seafloor consisted of several basins of variable size and topography, with depths ranging from m. Highly saline waters of greatly varying depth probably covered the bottom and deposited salts. The Gibraltar Sill is at waterdepth of 320 m.

28 Pliocene Africa The late Pliocene Vertebrate site of Ahl al Oughlam Geological map of the Casablanca area with dunes (yellow) along the main plio-pleistocene shores.

snakes, lizzards), primates (baboons, no hominoids), hyaenas, leopard, bats, cheetas, wild cats, foxes,

29 Late Pliocene (~2.6 MY) Casablanca The Ahl al Oughlam site is extremely rich in fossils. They include fish, sharks, dolphins, toothed whales, amphibians (frogs), reptiles (crocodiles, turtles, snakes, lizzards), primates (baboons, no hominoids), hyaenas, leopard, bats, cheetas, wild cats, foxes, otters, bears, walruses, rodents (rats and mice), shrews, hares, rabbits, elephants, camels, horses, giraffes, antelopes, gazellas...

Casablanca horse Hipparion is a primitive three-toed Equid, still having

The lateral toes show that this species had almost reached an Equus stage of

30 Casablanca horse Hipparion is a primitive three-toed Equid, still having lateral toes no longer present in Equus. It persists until about 0.5 My. in Africa. Ahl al Oughlam has yielded one of the best pliocene fossils of this group. The lateral toes show that this species had almost reached an Equus stage of evolution. During late Pliocene (2.6 MY), certain Equus species crossed from N America to the Old World. Some entered Africa and diversified into the modern zebras.

on the horse evolution chain to have only one toe.

31 Pliohippus Equus The Pliohippus lived during the Pliocene period and was the first of the mammals on the horse evolution chain to have only one toe. He is believed to be a direct ancestor to the Equus.

32 An unexpected find: walrus! Thewalrusisprobablythemost unexpected inhabitant of Ahl al Oughlam. Because of hunting, they are now restricted to the Arctic, but in prehistoric and historical times they reached as far south as Belgium. Ahl al Oughlam remains by far their southernmost record, and the only one in Africa. The walrus find raises interesting questions as to natural habitats of animals versus the effects of hunting...

33 References used when preparing this lecture Stanley: Earth System History. Arnold, London Fortey: Life. A Natural History of the First Four Billion Years on Earth. Vintage, New York. Einarsson, Þ Myndun og Mótun Lands. Jarðfræði. Mál og Menning. Buchard, B. & Símonarson, L.A. 2003: Isotope paleotemperatures from the Tjörnes beds in Iceland: Evidence of Pliocene cooling. Palaeogeography, Palaeoclimatology, Paleoecology 189,

Mesozoic Era 251 m.y.a 65.5 m.y.a

Mesozoic Era 251 m.y.a 65.5 m.y.a Mesozoic Cenozoic notes.notebook Mesozoic & Cenozoic 251 m.y.a Present at the end of the Permian, 90% of marine organisms and more than 70% of land organisms died. because resources and space were readily